Panel 3

Panel 4

Microwave PING!'s, a mutated Rupert breaks out with a GRAAAA!
Steve: "Uh... pizza?"

Fun Facts

The timer on the microwave reads "00:00" throughout this comic. As James explained, "It starts instantaneously after the end of the 2nd panel, and beaver speaks in the third panel just as it reaches zero. We see the zero before we hear the ping because light travels faster than sound. I have it all figured out." (Reference)